“BTW, tricked out AR-15s in 5.56mm have been cleaning up the thousand yard competitions for years now.”
I don’t doubt that a properly built and tuned AR-15 can hit a target at 1000 yards, but I don’t think a .22 caliber bullet carries enough energy at that distance to be useful.
They do with the right ammo, at least out to 800m. Apparantly the Black Hills 77gr 262 found a sweet spot, where accuracy is retained, but the bullets tumble on impact. (Unlike the 62gr green tips, and their notorious ice pick wounds.)
The proof is that snipers who have at hand a .308 bolt gun or an M16 designated marksmen rifle increasingly choose the M16 out to 800 yards. It’s sub MOA accurate, retains enough power to do the job, and in urban warfare it’s just light years quicker when engaging multiple movers.
“One shot one kill” is in a way a relic of the past, when you have multiple targets and only seconds to nail them before they scatter from view.
The 5.56mm... effectively wacking out bad-guys since it's first build out... Although my current AR is in 7.62x39
The modern day battlefield is taking place well within 800m, need to get beyond that? Time for the M1/M14.